XPS vs EPS: Product Comparisons & Value Engineering

It's important to understand the differences between XPS and EPS foam board in continuous insulation (ci) exterior wall systems.

Advanced Insulated Wall Systems — Part 2

As exterior insulation wall systems gain in popularity and demand, it’s important to differentiate between the options available to building professionals. The key words that count these days are “code compliance,” “continuous insulation,” “hydrophobicity,” “compressive strength,” and “R-Value.” Other desired benefits when comparing insulation for ci systems include moisture management, durability, and reduced energy costs.

While polystyrene-based insulation board products are often specified as part of a continuous insulation (ci) wall system, and some products may appear similar on the surface, the fact is, if you drill down into the science of insulated plastic sheeting, not all foam plastic insulations are the same.

 A quick primer on the differences between XPS and EPS

Extruded polystyrene foam insulation (XPS) is a high-performance, closed-cell rigid insulation, manufactured in a proprietary process that melts plastic resin and additives into a molten material that is extruded through a die where it expands and cools into a uniform closed-cell, rigid foam insulation board with no voids or pathways for moisture to enter. It is, therefore, inherently moisture-resistant or, in scientific terms, “hydrophobic.”

Molded bead expanded polystyrene (EPS) is made from small foam beads that are placed in a mold. These beards are exposed to steam while in the mold, which causes the beads to expand and stick together. This method of manufacture can result in interconnected voids between the beads, and these gaps can potentially provide pathways for water to penetrate the insulation. It is, therefore, not nearly as moisture resistant as XPS and could lead to degradation of the insulation’s performance.

The differences in composition and structure between the two insulation types can obviously affect the ultimate long-term performance, durability and efficiency of a ci-system wall. And yes, XPS is a more expensive, up-front investment than EPS, but before you “value engineer” it out of a project, you may wish to consider the long-term savings and benefits of its molecular structure and formulation.

Is XPS insulation the right product for your next EIFS wall?

Make an informed decision. The superior water resistance and higher lifetime R-value for XPS make it a compelling product to consider, as its performance compares favorably to the more commonplace molded bead expanded polystyrene (EPS).

The cost savings for EPS can be tempting, but it is also more susceptible to moisture intrusion and therefore not as durable. Another drawback: its R-value is rated “medium” versus “high.” (R-value is the measure of thermal resistance; the higher the R-Value, the greater the energy savings.) That means higher energy costs will be required to maintain the comfort level for the building’s occupants.

While the initial cost of an XPS system needs to be considered, its attributes will pay dividends when accounting for future energy savings and protection from moisture intrusion. An XPS system is also lighter weight, which makes for a low allowable deflection value. This savings and the fact that an XPS system is installation friendly with just one installer and a single skilled trade person required, also offsets the product cost, making XPS a more competitive option.

So when you weigh the options and lean in the direction of durability and efficiency, XPS becomes the logical choice.


Advanced Insulated Wall Systems that Exceed Expectations and Code

StoTherm ci XPS is a continuous insulation system, which provides air, thermal and moisture control without the connection and compatibility challenges that characterize other systems, while also offering multiple design and finish options.

Today’s architects, specification professionals, and owners are typically looking for an insulated wall design that not only meets but exceeds the nation’s increasingly demanding code requirements. Enter the StoTherm® ci XPS continuous insulation system, which provides air, thermal and moisture control without the connection and compatibility challenges that characterize other systems, while also offering multiple design and finish options.

As the building industry adopts more stringent energy codes (Title 24, IBC, IECC, ASHRAE 90.1), the need for external insulated finish systems (EIFS) is increasing. The StoTherm ci system is highly energy efficient, minimizing heating and cooling costs while reducing greenhouse gas emissions. The components prevent thermal bridging, thus lowering the risk of heat leakage and the attendant energy loss.

Other features that make the StoTherm ci XPS system a superior alternative to other systems include:

  • Durability and impact resistance (77% higher density and 250% higher compressive resistance than EPS)
  • Low Water Absorption (due to its closed cell structure)
  • R-Value of R5/inch (the higher the R-value, the greater the resistance to heat flow)

The system is also installation friendly; one installer and a single skilled trade person can make quick work of it. The low allowable deflection value makes for lightweight construction, which reduces overall project cost and weight per square foot.  These factors make for material and labor costs that are highly competitive, if not more economical than most other options.

A wide range of decorative and protective wall finishes (StoCreativ® Brick, granite, limestone) along with unlimited color choices make StoTherm ci XPS is one of the most versatile and innovative products on the market today.

Look for the second part in this series next week, which explores other advances in durable insulation products offered by industry leaders and several case studies that demonstrate their value add for building professionals and owners.


Aesthetically Enhanced Wall Solutions with StoPanel Dri-Design

The striking Dri-Design metal panels over Sto EIFS can be specified in a variety of materials, colors, finishes, dimensions and textures.

As a leader in wall cladding systems and the world’s largest manufacturer of insulated wall systems, Sto Corp is constantly looking for new and improved products and engineering solutions. One example of this is the StoPanel Dri-Design system, a next-generation exterior wall solution where form and function harmonize, offering all the advantages of panelization, and a superior moisture barrier with state-of-the-art water management. The easy-to-install, fully customizable system also offers a wide range of aesthetic options to choose from.

Manufactured with single-skin-metal, the StoPanel Dri-Design system employs an innovative and patented interlocking design that is attractive, adaptable and sustainable. The single-skin metal eliminates the risk of delamination or fire and will attach to nearly any substrate without clips or extrusions. Working with Dri-Design, Sto’s lightweight, energy-efficient and durable panel systems now offer even more aesthetic options while continuing to ensure optimum performance.

The Aloft / Element Hotel in downtown Austin, Texas is a showcase for the StoPanel Dri-Design exterior wall system consisting of 100% recyclable, pressure-equalized rain-screen, architectural metal panels. Available in a wide array of design possibilities, with an unlimited palate of colors, finishes, materials, and textures, these custom panels are manufactured efficiently and install faster than any comparable product, saving time and money.

As offsite manufacturing of panels rapidly gains in popularity due to faster build times and savings as much as 50% in labor costs, Sto Panel Technology now offers architects and builders even more options. The 33-story Aloft/Element Hotel in downtown Austin, Texas is one recent example of this pre-fab technology in action.  This hotel/retail development in the heart of Austin’s famed Entertainment District posed numerous challenges, including a zero-lot-line property located in a congested, busy downtown area, with no laydown area and an aggressive dry-in schedule.

The Baker Triangle Prefab project team for Aloft decided that Sto Panel Technology (STP) and Dri-Design’s metal wall panels offered the ideal workaround solutions – zero jobsite laydown, the ability to install a complete floor in just two days, with only a crew of 6 to install the building skin versus the customary crew of 55. All of the framing, sheathing, waterproofing, Dri-Design integration, EIFS, window units and window sealants were executed offsite where they were incorporated into each panel.

By eliminating the need for scaffolding and limiting the onsite manpower, safety and efficiency on site was improved, and by using Sto Panel’s digitized QA/QC program, the owner, project architect and other consultants could easily monitor all 600 panels. StoPanel Dri-Design was a “win-win” for all, delivering speed, value and quality.


Numbers Reveal Construction Industry Trends & Issues

Construction industry statistics from 2017 reveal future issues and trends to watch.

A picture is worth a thousand words, but statistics are also compelling — especially in an industry that’s driven by numbers. The following numerical data, as reported by Construction Dive, are based on a recap of 2017; they are noteworthy in billboarding the near future for construction.

$1.6 trillion — The opportunity cost, according to McKinsey Research, of the construction industry’s hesitation to adopt new technology. While new technologies are making inroads in the construction market – drones, and high-tech, virtual reality  & AR wearable devices – the industry remains somewhat old-school and slow to adapt, thus missing opportunities to grow the market.

$200 billion – According to Moody’s, the estimated damage from Hurricanes Harvey and Irma that ravaged Texas and Florida this year. The stat is a strong argument for resilient design and planning for extreme weather events and rising sea levels.

Key West, Florida, underwater.

$5 billion — The amount of money Amazon is planning to put into its second headquarters (HQ2) building, location TBD.

1,200 — The number of concrete buildings that fall under Los Angeles’ seismic retrofit ordinance, which is the first of its kind in the country. Another tale of governmental policies that are shaping the construction industry and driving resilient design standards to ensure public safety, while protecting property owners’ investments.

76 — The percentage of U.S. construction companies that indicate the tight labor market will stay the same or worsen throughout the year. This statistic, unveiled by the Associated General Contractors of America, bodes well for next-generation practices such as off-site construction, prefabrication and modular assembly, that have proven to help mitigate the industry’s persistent skilled labor shortage.

56 — The average age of the more than 90,000 dams in the U.S. The Association of State Dam Safety Officials estimates the necessary work on the country’s non-federal and federal dams would cost more than $64 billion.  Now there’s a construction market opportunity!

3 — The number of months it took to 3-D print a 26-foot-long concrete bridge in the Netherlands comprised of 800 layers of reinforced, pre-stressed concrete material. 3-D printing and comparable new technologies are changing the building industry.


AIA Announces Architecture Honor Awards for 2018

The highly innovative Spring Street Salt Shed, in Manhattan, by Dattner Architects in association with WXY architecture + urban design, was also honored. This New York City industrial facility was transformed into urban art; “a visual oxymoron to sanitation” said the judges who applauded the project for raising the bar on civic infrastructure design.

The American Institute of Architects (AIA) has announced its Honor Award winners for 2018, which include projects from around the world designed by architectural firms both large and small. From a girls’ school in Afghanistan to a municipal salt shed, this year’s widely diverse group of winning projects will be honored at the AIA Conference on Architecture in New York City in June of this year. The Honor Awards, now in their 69th year, were selected by a jury consisting of architects and academics who judged projects based on “outstanding excellence and innovation”.

The Audain Art Museum in Whistler, British Columbia, Canada by Patkau Architects was one of the 17 award winners. An eco-friendly design, the elegant architectural structure hovers above a floodplain topography where there is heavy snowfall, thus embracing the elements and the setting. According to the judges, the project “wraps users around nature, blurring the boundaries between man-made and natural”

Another award-winning museum was The Broad in Los Angeles, designed by architects Diller Scofidio + Renfro in collaboration with Gensler.  The contemporary art museum is home to more than 2,000 works of art in the Broad collection, one of the most prominent holdings of postwar and contemporary art worldwide. The 120,000-square-foot building features two floors of gallery space.

The Chicago Riverwalk, by Ross Barney Architects & Sasaki Associates, also took top honors. A once neglected downtown riverfront area, it is now a reinvented urban space with a wide range of amenities that reflect the city’s layered and diverse history.

Another award-winner was the Gohar Khatoon Girls’ School, in Mazar-i-Sharif, Afghanistan, designed by Robert Hull, FAIA, and the University of Washington, Department of Architecture. A modern take on masonry construction, the school’s beautiful yet restrained aesthetic creates an urban oasis and promotes community engagement as well as reflecting a new era for girls and women in the country.

Other architectural design winners were: the Mercer Island Fire Station 92, in Washington by Miller Hull; the new United States Courthouse by Skidmore, Owings & Merrill in Los Angeles; the Vol Walker Hall & the Steven L. Anderson Design Center, a state-of-the-art architecture, landscape architecture and interior design school, by in Fayetteville, Arkansas, designed by Marlon Blackwell Architects; and the Washington Fruit & Produce Company Headquarters, in Yakima, Washington, by Graham Baba Architects.